Calcium

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Calcium
20Ca
Mg

Ca

Sr
potassiumcalciumscandium
Appearance
dull gray, siller


Spectral lines o calcium
General properties
Name, seembol, nummer calcium, Ca, 20
Pronunciation /ˈkælsiəm/ KAL-see-əm
Element category alkaline yird metal
Group, period, block 2 (alkaline earth metals), 4, s
Staundart atomic wicht 40.078(4)
Electron confeeguration [Ar] 4s2
2, 8, 8, 2
Electron shells of calcium (2, 8, 8, 2)
History
Discovery Humphry Davy (1808)
First isolation Humphry Davy (1808)
Physical properties
Phase solid
Density (near r.t.) 1.55 g·cm−3
Liquid density at m.p. 1.378 g·cm−3
Meltin pynt 1115 K, 842 °C, 1548 °F
Boilin pynt 1757 K, 1484 °C, 2703 °F
Heat o fusion 8.54 kJ·mol−1
Heat o vaporization 154.7 kJ·mol−1
Molar heat capacity 25.929 J·mol−1·K−1
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 864 956 1071 1227 1443 1755
Atomic properties
Oxidation states +2, +1[1]
(strongly basic oxide)
Electronegativity 1.00 (Pauling scale)
Ionization energies
(more)
1st: 589.8 kJ·mol−1
2nt: 1145.4 kJ·mol−1
3rd: 4912.4 kJ·mol−1
Atomic radius 197 pm
Covalent radius 176±10 pm
Van der Waals radius 231 pm
Miscellanea
Crystal structure face-centered cubic
Calcium has a face-centered cubic crystal structure
Magnetic orderin diamagnetic
Electrical resistivity (20 °C) 33.6 nΩ·m
Thermal conductivity 201 W·m−1·K−1
Thermal expansion (25 °C) 22.3 µm·m−1·K−1
Speed of sound (thin rod) (20 °C) 3810 m·s−1
Young's modulus 20 GPa
Shear modulus 7.4 GPa
Bulk modulus 17 GPa
Poisson ratio 0.31
Mohs hairdness 1.75
Brinell hairdness 167 MPa
CAS registry nummer 7440-70-2
Most stable isotopes
Main article: Isotopes o calcium
iso NA hauf-life DM DE (MeV) DP
40Ca 96.941% >5.9×1021 y β+β+ 0.194 40Ar
41Ca trace 1.03×105 y ε - 41K
42Ca 0.647% 42Ca is stable wi 22 neutrons
43Ca 0.135% 43Ca is stable wi 23 neutrons
44Ca 2.086% 44Ca is stable wi 24 neutrons
45Ca syn 162.7 d β 0.258 45Sc
46Ca 0.004% >2.8×1015 y ββ 0.988 46Ti
47Ca syn 4.536 d β 0.694, 1.99 47Sc
γ 1.297 -
48Ca 0.187% 4.3×1019 y ββ 4.274 48Ti
β
(nae observed)
0.0058 48Sc
· r

Calcium is the chemical element wi seembol Ca an atomic nummer 20. Calcium is a saft gray alkaline yird metal, an is the fift-maist-abundant element bi mass in the Yird's crust. Calcium is an aa the fift-maist-abundant dissolved ion in seawatter bi baith molarity an mass, efter sodium, chloride, magnesium, an sulfate.[2]

Calcium is essential for livin organisms, in particular in cell physiology, whaur movement o the calcium ion Ca2+ intae an oot o the cytoplasm functions as a signal for mony cellular processes. As a major material uised in mineralization o bone, teeth an shells, calcium is the maist abundant metal bi mass in mony ainimals.

References[eedit | eedit soorce]

  1. Krieck, Sven; Görls, Helmar; Westerhausen, Matthias (2010). "Mechanistic Elucidation of the Formation of the Inverse Ca(I) Sandwich Complex [(thf)3Ca(μ-C6H3-1,3,5-Ph3)Ca(thf)3] and Stability of Aryl-Substituted Phenylcalcium Complexes". Journal of the American Chemical Society 132 (35): 100818110534020. doi:10.1021/ja105534w. PMID 20718434. 
  2. Dickson, A. G. and Goyet, C. (1994). "5". Handbook of method for the analysis of the various parameters of the carbon dioxide system in sea water, version 2. ORNL/CDIAC-74. 

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